Seismic Responses of Two Adjacent Buildings. I: Data and Analyses

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Abstract
In this two‐part paper, responses of two, adjacent, seven‐story buildings in Norwalk, California, to the Whittier‐Narrows, Calif. earthquake of Oct. 1, 1987 are studied. Building A, instrumented according to code recommendations, and building B, extensively instrumented, are offset by 16.3 m from one another. The data set includes motions from the superstructure of both buildings, from a downhole below the foundation of building B, and from three free‐field sites. Part I of the paper includes descriptions of the buildings, site, instrumentation, and analysis of the data of each building. System identification and spectral analysis techniques are employed in part I. Building A has identical first‐mode frequencies of 0.65 Hz for both building axes. The strong‐motion response characteristics of building A are considerably different than those determined from low‐amplitude tests. Building B has fundamental modes at 0.76 Hz and 0.83 Hz in the major and minor axes, respectively. Torsional and diaphragm effects in building B are negligible.